Feed mechanism for phonograph recorders



y 1934- H, c. HARRISON ,959,423

FEED MECHANISM FOR PHONOGRAPH RECORDERS Filed Sept. 1, 1933 FIG.

IN VE N TOR H. c. HARRISON A 7' TORNEV Patented May 22, 1934 FEED MECHANISM FOR PHONOGBAPH BECORDERS Henry 0. Harrison, Port Washington, N. Y., assignor to Bell Telephone Laboratories, Incorporated, New York,'N. Y., a corporation of New York Application September 1, 1933, Serial No. 687,739

8 Claims. (01. 274-43) a phonograph the machine ordinarily can not be used to record sound. Ina number of instances, however, it would be desirable to use the same machine for both recording and reproducing purposes and if absolute simplicity is not achieved in the design of the recorder feed such a combination is not feasible.

'A simple form of stylus feed for a recorder that has been proposed in the past is a pregrooved record blank having a plain spiral groove cut in its surface which is followed by a recording stylus and modified thereby in accordance with the movement of the stylus. Although this type of blank does eliminate the usual feed mechanism and thus removes the mechanical distinction between the recording and reproducing phonograph it has this disadvantage in that the recording action of the stylus is restricted and influenced by the walls of the feed groove with a consequent infidelity of recording. To feed the recorder by means of a follower and groove concentric with the record groove, 1: 1t external to the record to eliminate this disadvantage requires additional linkages and mechanisms which are undesirable.

The object of this invention is a means for feeding a recorder across a record blank which uses a minimum of mechanisms and does not cause the recording stylus to operate in preformed grooves.

The theory on which this invention is based is similar to that underlying the action of a threading die in cutting a thread. A portion of the thread is first out under pressure and the portion of the thread so formed then becomes a guide for the die in cutting the remainder of the thread, each fragment of the thread as it is out being used to cut an additional new fragment.

According to this invention, therefore, the record blank is pregrooved over a small portion of its margin and this pregrooved portion coacts with a follower rigidly secured to the recorder, the stylus of which cooperates with the uncut portion of the blank and as the blank is rotated, the follower moves across the blank under the action of the groove already formed and thus causes the stylus likewise to move, thereby cutting a fresh groove which in turn is used by th; follower to cut additional grooves. This action is automatic and continues until the recorder is lifted from the record or the rotation of the record is stopped.

A preferred form of the invention is illusstrated in the accompanying drawing in which: Fig. 1 is a plan view of a record pregrooved in accordance with this invention; Fig. 2 is a front elevation of a recorder showing the novel driving means attached thereto; and,

Fig. 3 is a side elevation of the recorder and driving means of Fig. 2. 7

The record blank 10 of Fig. 1 may be either rigid or flexible, provided, however, that it is made of a material which is sufficiently tough to withstand the rubbing action of the novel driving means without an appreciable change in 'the form of its surface, and particularly, in the form of the groove cut therein. It need not be a disc, but may take other shapes, such for example, as a cylinder. The blank 10 is apertured at 11 to receive a centering pin in the usual manner. At the outer margin of the central portion of the record blank is stamped or otherwise formed a plain spiral groove 12. The pitch of the spiral is made the same as the pitch at which it is desired to' record, since it is this short section of the groove that starts the recorder across the remaining portion of the rec-' 0rd blank and determines the pitch of the groove to be cut. With the plain groove located as shown, the recorder is. fed from the center out- 95 ward. This is the preferred location for the groove because it then occupies a portion of the blank which is ordinarily useless for recording purposes and it therefore does not encroach upon any of the space that can be used for recording purposes.

The number of turns of the plain groove 12 necessary for the operation of this invention is determined by the width of the novel driving member hereinafter described and the distance 5 is actuated by sound controlled electrical 'currents generated in a pick-up 23 and strengthened in amplifier 24. The support for the recorder may be either a sliding carriage or a pivoted arm and since both varieties are well known in the art and are equally effective in the operation of this invention no support is shown. A recording stylus 14 driven by the recorder 13 is shown in the groove of the record blank 10, and for the sake of completeness, a turntable 15 is shown supporting the record blank.

Secured to the side of the recorder 13 is a guide 16 for a vertical pin 17 by virtue of which the pin 1'7 is free to move vertically, but is restrained horizontally, with respect to the stylus 14. The pin extends above and below the guide 16. At its upper end is a shoulder formed by a knurled nut 18 which limits the downward motion of pin 1'7. The greater portion of guide 16 is bored to a larger diameter than the diameter of pin 1'7 to receive the machined shank 25 of an adjusting nut 21 which is threaded over the lower portion of pin 17, and in the space between the pin 17 and guide 16 is a helical spring 20 which serves to maintain a steady downward pressure upon the slidable adjusting nut 21.

At the lower end of pin. 17 is secured the principal driving means for the recorder 13. It is comprised of a small brush 19 having an area of approximately one quarter of a square inch in contact with the groove in the record blank 10. The bristles of the brush are of uniformly varying length with an average length of about A; inch and arranged so that the shortest bristles enter the groove first. This form of brush has been found to produce the least chattering and the most positive driving action. The diameter of the individual bristles is small enough to enable the bristles to enter the groove. The bristles should be softer than the record blank material over which they are rubbed so that the material is not scratched or deformed by the rubbing action. Although the driving force derived from each bristle is small, enough bristles are contained in the brush to provide the requisite driving force for the recorder.

The driving means is shown and described as a brush, but I have found that any fibrous material, such, for example, as felt, with a sufllcient area in contact with the groove may be used for this purpose.

From the position of the driving member 19 relative to the stylus 14 it is now apparent that the grooved portion 12 of the record 10 should extend from the stylus 14 to a point just beyond the left hand edge of driving member 19 so that thereis a continuous groove under stylus 14 and under the whole of driving. member 19.

To maintain a uniform pitch the driving member 19 and the stylus 14 should both lie on, and follow, a common radius of the record blank 10. The space between driving member19 and the stylus 14 shoud be as small as possible to lessen the amount of space used for the blank groove 12.

The operation of the device requires no more skill than is necessary to operate an ordinary phonograph. The pregrooved record 10 is placed upon turntable 15. and is centered thereon by slipping centering pin 22 through aperture 11. Next, stylus 14 of recorder 13 is set near the outer edge of the grooved portion 12 which, by virtue of the rigid connection between the stylus and driving member 19, automatically places the latter upon the grooved portion 12 also. The

Y groove 12, but it'soon leaves this groove and blank, a self -feeding recorder comprising a stylus recording, however, but while the record blank is rotating, it is advisable to wait until stylus 14 coacts with the uncut portion of theblank 10 so that the stylus cuts or records uninflu-" enced by any preformed groove. The driving member 19 first coacts with the preformed $5 enters thegroove just cut by the stylus, which continues smoothly from the end of groove 12, and derives its driving force from the walls of the stylus-cut groove just as it did from the walls of the preformed groove. The feeding action then continues as long as the driving member 19 is in contact with the groove and the record blank is rotating. To stop the feeding action it is necessary either to stop the rotation of the record blank or to raise the recorder and the attached driving member 19 from the record blank.

It is apparent to those skilled in the art that this invention is susceptible of many variations and its scope therefore is not to be limited by the illustrative example set forth above, but it is tobe defined entirely by the appended claims.

What is claimed is:

1. In combination, a recorder, a rotatable partially grooved record blank and means for using the groove in the record blank todrive the recorder across the remainder of the uncut record Blank while the latter is rotating.

2. A rotatable partially pregrooved record cooperating with the uncut portion of the record blank, and a follower member secured to the stylus and cooperating with the grooved portion of the record blank, whereby the stylus is driven across the record blank by the action 5 of the walls of the groove upon the follower member when the record blank is rotated.

3. A rotatable record blank having less than fifty-per cent of the usable surface thereof cut v with a plain groove, means engaging the grooved portion of the record blank, a recording stylus connected to said means and cooperatingzwith the uncut portion of the record blank, whereby said means is caused to drive the recording stylus across more than fifty per cent of the surface of the record blank by the action of the walls of the groove upon the means when the record blank is rotated.

4. A rotatable record blank containing a spiral groove of less turns than the number of turns of the proposed recording, a recorder cooperating.

with the record blank, a feed mechanism for the recorder comprising a multiple stylus member secured to the recorder and cooperating with the grooved portion of the record blank, whereby the recorder is driven uniformly across the surface of the blank when the latter is rotated.

5. A rotatable partially grooved record blank, a recording stylus cooperating with the record blank and means comprising a brush secured to the recording stylus and engaging the grooved portion of the record blank for driving the reccorder across the uncut portion of the record blank when said record blank is rotated.

6. A rotatable record blank containing a grooved portion at a margin thereof of less turns than the number of turns of the proposed record-containing portion, a groove recorder o cooperating with the uncut portion of the blank, means for feeding the recorder laterally comprising a pad of fibrous material secured to the recorder and cooperating with the grooved portion of the blank whereby the pad and the recorder are driven uniformly across the record blank when the latter is rotated.

7. A rotatable disc record blank, a groove on the record blank located at a portion of the blank normally unused for recording because of the low linear velocity obtaining thereat, a follower engaging, the groove, a recorder cooperating with the uncut portion of the record blank and means for securing the follower to the recorder whereby the recorder is driven across the record blank when .the latter is rotated.

8. In combination a recording stylus, a disc record blank, means for rotating the record blank and means for driving the stylus across the surface of the blank, said means comprising a brush secured to the stylus and adapted to move perpendicularly to the record blank surface to follow undulations therein. a spiral groove located within the normally unused central portion of the record blank and of a sufficient number of turns to cause it to extend continuously under the stylus and brush and spring means for maintaining contact between the brush and groove when the stylus coacts with the record blank, whereby the walls of the groove are used to feed the brush and stylus laterally.

HENRY C. HARRISON.

its 

